The Safety of Air Ambulances

27 Pages·2006·0.13 MB·English

by  May 23, 2006

Order Code RL33430
CRS Report for Congress
Received through the CRS Web
The Safety of Air Ambulances
May 23, 2006
Bart Elias
Specialist in Aviation Safety, Security, and Technology
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress
The Safety of Air Ambulances
Summary
The estimated rate of air ambulance accidents has been steadily rising since the
early 1990s, and has increased at a rapid rate since 1998 when the industry began to
expand more rapidly and shift toward a model of more independent private air
ambulance services that cover larger geographic areas. Statistics indicate that the
large majority of air ambulance accidents are attributable to operational factors
related to pilot situation awareness and decision making when faced with adverse
environmental conditions such as darkness, deteriorating weather, rugged terrain, or
some combination of these factors.
Initiatives to improve air ambulance safety to date have consequently focused
on additional pilot training, implementing risk management practices to improve the
safety of flight operations, and using various technologies to improve pilot situation
awareness in restricted visibility conditions. However, implementation of these
safety measures has strictly been voluntary. The National Transporation Safety
Board (NTSB) and other aviation safety experts are advocating the mandatory use of
formal flight dispatch procedures and risk management practices among air
ambulance operators as well as mandatory installation of terrain warning systems on
air ambulance aircraft. The NTSB also found that many air ambulance accidents
occur when patients are not on board, such as en route to an accident scene. Present
regulations allow air ambulances to operate under a less stringent set of rules with
regards to weather minimums and pilot duty times when not carrying patients.
However, the NTSB believes that air ambulance flights should operate under more
stringent commercial operating rules at all times that medical personnel are carried
on board. Although maintenance issues have been identified in about 20 percent of
all air ambulance accidents, neither the Federal Aviation Administration (FAA) nor
the NTSB has placed any specific emphasis on oversight of operators or repair
stations that maintain air ambulance aircraft. The present emphasis on air ambulance
safety has, instead, been dominated by concerns over flight crew performance and
weather-related factors.
A variety of options are available to improve safety among air ambulance
operators. These options include intensified oversight of air ambulance operators and
regulatory changes to bring all phases of air ambulance operations under the same set
of operational rules regarding weather minimums and pilot duty times; possible
regulatory changes to provide for sharing and analysis of safety-related data and
observations with some degree of impunity; possible aircraft design considerations
to improve crash survivability; expanded application of system safety and formal
risk management principles to mission planning and flight operations; enhanced
training for both pilots and support personnel and operational procedures to improve
coordination and situation awareness among the entire air ambulance crew and
ground support team; and the use of various technologies to improve pilot situation
awareness and augment pilot vision in low visibility conditions.
This report will not be updated.
Contents
An Analysis of Air Ambulance Safety Data .............................1
The Role of Air Ambulances .........................................5
State of the Air Ambulance Industry ...................................7
Causes of Air Ambulance Crashes.....................................9
Interaction Between Pilots and Flight Conditions ................10
Pilot Situation Awareness of Weather Conditions ...............11
Mission Pressures ........................................11
Conditions in the Flight Environment .........................13
Mechanical Failures and Maintenance Related Crashes ...........14
Options for Improving Safety .......................................14
Regulatory Standards and Oversight ..............................14
Conducting Special Emphasis Inspections .....................15
Applying Consistent Regulatory Requirements During All Phases of
Operation ...........................................16
Addressing Concerns Over Pilot Fatigue .......................16
Increasing Maintenance Oversight ............................18
Improving Aircraft Crashworthiness ..........................18
Implementing System Safety and Risk Management Principles .........19
Training and Procedures for Flight and Medical Crews ...............20
Technology to Improve Safety in Low Visibility Conditions ..........22
Terrain Warning Systems ...................................23
Technologies to Enhance In-Flight Visibility ...................23
List of Figures
Figure 1. Three-Year Moving Average of Estimated Overall and Fatal Accident
Rates for Helicopter Air Ambulance Operations ......................3
Figure 2. Factors in Helicopter Air Ambulance Accidents
(1991 -2004) .................................................10
The Safety of Air Ambulances
Air ambulances that conduct emergency medical service operations and other
medical-related transport services include both helicopter emergency medical
services (HEMS) that primarily conduct scene response transport of trauma patients
and fixed-wing aircraft operations that primarily conduct inter-facility transports of
critical care patients. The air ambulance industry has grown significantly over the
past 25 years and is widely regarded as having a beneficial effect on improving the
chances of survival and recovery for trauma victims and other critical patients,
especially in rural areas. However, during this time, the air ambulance industry has
been the focus of two in-depth National Transporation Safety Board (NTSB) special
safety studies and numerous other investigations by aviation safety researchers that
have pointed to continued concerns over the safety of its flight operations,
particularly among helicopter air ambulance operators. Although the air ambulance
industry and Federal Aviation Administration (FAA) regulators have taken some
positive steps to address continued concerns over operational safety, the NTSB and
some other aviation safety experts have voiced concerns that not enough has been
done to reduce the risk of accidents in air ambulance operations.
This report analyzes available air ambulance safety data, examines the current
state of the air ambulance industry and factors that may influence safety within the
industry, assesses causal factors underlying the recent spate of air ambulance crashes,
and discusses some available options for improving safety.
An Analysis of Air Ambulance Safety Data
A recent increase in the number of crashes involving air ambulances has raised
concerns among aviation safety experts. According to a National Transportation
Safety Board (NTSB) special study focusing on aviation emergency medical
operations released in January 2006, 55 crashes involving air ambulances occurred
in the United States between January 2002 and January 2005.1 The NTSB noted that
this number of crashes has not been seen since the 1980s. Given that the current air
ambulance fleet is estimated to consist of about 750 helicopters and 150 fixed wing
aircraft,2 each year over the past three years, about one in every 50 helicopter air
ambulances has been involved in a crash. An article in USA Today offered the
following stark analogy: “If commercial airlines lost the same proportion of large
1 National Transportation Safety Board, Special Investigation Report on Emergency Medical
Service Operations. NTSB/SIR-06/01.
2 Foundation for Air-Medical Research & Education (FARE), Air Medicine: Accessing the
Future of Health Care, Alexandria, VA: FARE, 2006.
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passenger jets as air ambulance companies lost helicopters, 90 airliners would crash
each year.”3
Because there is no centralized database of flight records for the air ambulance
industry, no one knows for sure if safety is eroding or if this increase in accidents can
be explained by the large growth in the use of helicopters and airplanes for medical
evacuation and patient transport. The NTSB notes that while industry estimates
suggest that the number of hours flown by air ambulances has increased by about
85% over the past 15 years, the estimated accident rate for helicopter air ambulances
has also risen from 3.52 accidents per 100,000 flight hours between 1992 and 2001
to 4.56 accidents per 100,000 flight hours between 1997 and 2001.4 The NTSB,
however, did not provide its own estimates of accident rates or more recent figures
on the annual accident rates for air ambulances.
Available accident statistics and analyses reviewed by CRS have focused on
helicopter air ambulance operations, which make up more than 80% of the air
ambulance fleet. Consequently this report concentrates on safety data and finding
related to helicopter air ambulances, although many of the issues and observations
may be more broadly applicable to both helicopter and fixed-wing air ambulances.
While much of the flight hour data to substantiate accident rate statistics for air
ambulance operations remains sketchy, CRS analyzed helicopter air ambulance
safety data and computed accident rates using accidents between 1991 and 2004
identified in the 2006 NTSB special study report, and accident data and industry
estimates of hours flown by helicopter air ambulance operators cited in a
comprehensive safety review and risk analysis of air ambulance accidents published
by the Air Medical Physician Association (AMPA).5 This analysis estimated that the
overall accident rate among air ambulance operators from 1991 to 2004 to be 3.50
accidents per 100,000 flight hours and the fatal accident rate to be 1.13 accidents per
100,000 flight hours. Looking only at the data since 1998 when a notable spike in
accidents was first observed, the estimated overall accident rate rose to an average
of 4.75 accidents per 100,000 flight hours and the estimated fatal accident rate
increased slightly to 1.25 accidents per 100,000 flight hours. Three-year moving
averages of the estimated accident rate were computed across the 14 year period
3 Alan Levin and Robert Davis, “Surge in Crashes Scars Air Ambulance Industry.” USA
Today, July 18, 2005, A1.
4 Ibid. See also Ira J. Blumen, M.D., and the University of Chicago Aeromedical Safety
Committee, A Safety Review and Risk Assessment in Air Medical Transport, 2002, Air
Medical Physicians Association, Salt Lake City, UT.
5 CRS analysis of annual accident data and flight hour estimates provided in National
Transportation Safety Board, Special Investigation Report on Emergency Medical Service
Operations and Ira J. Blumen, M.D., and the University of Chicago Aeromedical Network.
A Safety Review and Risk Assessment in Air Medical Transport, 2002. Note: for 2002
through 2004, CRS interpolated estimated flight hours based on industry flight hour
estimates provided for previous years and an estimate of 300,000 hours flown in 2005 cited
in the NTSB report. This yielded an average annual increase in flight hours between 2001
and 2004 of roughly 9.3%.
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based on available flight time estimates and are shown in Figure 1.6 The trend in the
three-year moving average accident rates suggests a steady increase in the accident
rate from 1991 through 2003, with a slight reversal of this trend in 2004. The data
also show a slight rise in the fatal accident rate over the past five years. While these
data demonstrate an increase in helicopter air ambulance accident rates, particularly
since 1998, they cannot be regarded as conclusive because of the lack of reliable data
on the overall number of hours flown. However, these data, based on best available
information, strongly suggest that there is cause for concern regarding the safety
trend for air ambulance operations.
Figure 1. Three-Year Moving Average of Estimated Overall and Fatal
Accident Rates for Helicopter Air Ambulance Operations
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Sources: CRS analysis of annual accident data and flight hour estimates provided
in National Transportation Safety Board, Special Investigation Report on
Emergency Medical Service Operations. NTSB/SIR-06/01 and Ira J. Blumen,
M.D., and the University of Chicago Aeromedical Network. A Safety Review and
Risk Assessment in Air Medical Transport, 2002, Air Medical Physicians
Association, Salt Lake City, UT. Note: A three-year moving average computes
the accident rate using the data from the current year and the two prior-years.
There are two key concerns regarding these accident rate estimates. First, the
trend shows a steady increase in estimated accident rates over the past 14 years, with
6 A three-year moving average, sometimes referred to as a three-year rolling average, is an
accident rate calculation based on accidents and flight hours during the referenced year and
the two prior years. So, for example, the data points for 1993 are based on accidents and
flight hour estimates for 1991, 1992, and 1993. This is done to provide a more stable metric
for analyzing trends among accident rates that may fluctuate significantly from year to year.
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a more marked increased since 1998. Second, these estimated accident rates are
notably higher than many other commercial aviation sectors. In particular, over the
same period (from 1991-2005), non-scheduled air taxi operators, which fly under the
same rules as air ambulance operators carrying patients, experienced an overall
accident rate of 2.52 accidents per 100,000 flight hours and a fatal accident rate of
0.67 fatal accidents per 100,000 flight hours.7 While air ambulance operations,
particularly helicopter air ambulance operations, by their nature may arguably be
inherently more risky than other commercial aviation operations, the relatively higher
estimated accident rates coupled with the observed trend of increasing accidents and
estimated accident rates suggests that the causes of these accidents and possible
options to reduce these numbers is an appropriate topic for policy analysis.
When the NTSB previously examined commercial emergency medical service
helicopter operations in 1988, it estimated that the overall accident rate between 1980
and 1985 was 12.34 per 100,000 flight hours, almost twice the estimated accident
rate experienced by non-scheduled helicopter air taxis during that period.8 Moreover,
the fatal accident rate of 5.40 per 100,000 flight hour for helicopter air ambulances
between 1980 and 1985 was estimated to be about 3 ½ times the fatal accident rate
for non-scheduled helicopter air taxis and all turbine-powered helicopters.9 While
more recent accident rate estimates among helicopter air ambulance operators have
been climbing steadily, they still appear to be much lower than estimates for the early
1980s. However, the lower observed accident rates in the early 1990s suggest that
safety improvements can be made in air ambulance operations to reduce the overall
and fatal accident rates compared to recently observed levels. Specifically, between
1991 and 1995, the helicopter air ambulance industry had an estimated 1.81 accidents
and 0.91 fatal accidents for every 100,000 flight hours, accident rates that closely
resemble those of other commercial aviation operations such as the previously cited
statistics for non-scheduled air taxi operators. Arguably, based on these data, the
helicopter air ambulance industry has already demonstrated that it can achieve a
better safety record than what it has experienced since 1998.

Although air ambulance operations can be inherently riskier than other aviation
operations because the environment in which they operate is more dynamic and
unpredictable, some experts have raised concerns that the air ambulance industry and
the FAA are simply accepting a higher accident rate than other areas of the aviation
industry rather than taking steps to reduce the number of accidents.10 While the FAA
and the air ambulance industry have acknowledged that ongoing safety concerns
7 Both non-scheduled air taxi operators and air ambulance operations with patients on board
are conducted under Title 14 Code of Federal Regulations, Part 135. CRS calculations
based on data provided in: National Transportation Safety Board, Accidents, Fatalities, and
Rates, 1986 - 2005, 14 CFR Part 135, Nonscheduled Service (On-demand Air Taxis).
8 Non-scheduled helicopter air taxi are operated under Title 14 Code of Federal Regulations,
Part 135 and generally do no include local air tours that are exempt from operating under
this set of regulations.
9 National Transportation Safety Board, Commercial Emergency Medical Service Helicopter
Operations, NTSB/SS-88/01.
10 Alan Levin and Robert Davis, “Surge in Crashes Scars Air Ambulance Industry.”
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exist, critics argue that their actions to date — largely consisting of advisory
materials and recommendations requiring only voluntary compliance by operators —
are inadequate. To further assess the root causes of air ambulance accidents and
assess possible policy changes to improve safety in the air ambulance industry, it may
be beneficial to examine the operational role of air ambulances as well as the current
state of the air ambulance industry and management practices in the air ambulance
industry.
The Role of Air Ambulances
When most people think of an air ambulance operation they are likely to first
consider helicopter transports of trauma patients, such as car accident victims. This
has historically been the predominant form of air ambulance service since its
beginnings in the early 1970s. Large scale use of air evacuation of wounded troops
was demonstrated to be an effective means of reducing combat mortality both in the
Korean and Vietnam conflicts. Based on this experience, civilian air ambulance use
in the United States began on a small scale starting in the early 1970s and has grown
significantly since. Although some studies have found little or no benefit from
helicopter evacuations of civilian trauma patients, numerous studies point to
improved chances for recovery and significant reductions in mortality rates when air
ambulance services are made available to trauma patients.11 Medical theory and
practice holds that providing critically injured patients with surgical intervention
within the first hour after injury – the so-called “Golden Hour” – can significantly
improve the chances for survival and recovery.12 In practice, air ambulances,
particularly helicopters, can play an important role in this intervention by providing
rapid patient transport to trauma centers where they can be effectively treated, and
in some cases providing advanced life support capabilities en route. The availability
of this service provides an important role, especially in rural communities that lack
readily accessible advanced care facilities and medical specialists.
More recently, there has been increased utilization of air ambulances, both
helicopters and airplanes, for both on-scene response and inter-facility transport of
critical cardiac patients and stroke victims. Both helicopters and fixed-wing aircraft
are also utilized for other inter-facility transfers to give patients access to specialty
care facilities and medical specialists. While the on-scene response of a helicopter
at a traffic accident is probably what first comes to mind when the term air
ambulance is used, today about 54% of all air medical transports are from hospital
to hospital, while on-scene responses make up 33%. The remaining 13% include
organ and medical supply and speciality medical team transports.13 Air ambulances
can also play an important role in emergency evacuation of critical care patients and
11 Association of Air Medical Services (AAMS), AAMS Brief – Part 3: Air Medical
Research and What It Shows. Alexandria, VA: AAMS; National Transporation Safety
Board, Commercial Emergency Medical Service Helicopter Operations; Foundation for Air-
Medical Research & Education (FARE), Air Medicine: Accessing the Future of Health
Care.
12 Foundation for Air-Medical Research & Education (FARE), Air Medicine.
13 Ibid.
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transport of medical supplies and staff to disaster areas, as was demonstrated in the
aftermaths of Hurricanes Katrina and Rita in 2005.14
While some critics assert that air ambulance transports are being over utilized,15
there is generally widespread acceptance of the benefit provided by both the general
public and the medical community. The air ambulance community acknowledges
that utilization of air ambulances in some cases may, in retrospect, prove to have
been unnecessary. This, they argue, is to be expected if the medical community is
to assure that the maximum number of patients who could potentially benefit from
air ambulance services are provided with this service. Over the past 15 years,
guidelines for air medical dispatch have been refined by the air ambulance
community and emergency room physicians. These various guidelines set forth
circumstance-specific and patient-specific criteria for decision makers assessing
whether to dispatch a flight as well as for analysts reviewing and modeling utilization
and refining resource allocation across a particular geographic area.16 The industry
also argues that while air ambulance services are comparatively costly when
examined on a single-case basis, appropriately used air medical transport is cost-
effective on a system-wide basis, largely due to more efficient coverage of large
geographic areas, reduced patient transport times, and more rapid intervention that
can reduce overall patient care costs.17 In general, air ambulance services have
garnered wide community support and endorsement from the medical community as
being a beneficial and cost-effective service for improving access to critical health
care and increasing the chances of survival and recovery for trauma victims and
critically ill patients, particularly in areas where access to specialized health care is
limited. Consequently, air ambulance utilization is likely to continue its steady
growth throughout the United States, particularly in rural areas. This expectation of
continued growth for the industry draws particular attention to the ongoing safety
concerns, because continued growth without any improvement to safety could trigger
widespread public concern over the safety of these operations which has already been
evidenced to some degree based on recent media coverage of the issue.18
State of the Air Ambulance Industry
The civilian air ambulance industry can trace its origins back to the early 1970s
with the creation of the Maryland State Police aviation program in 1970 and the first
hospital-based medical helicopter service at St. Anthony’s Hospital in Denver,
Colorado in 1972. Prior to then, police departments in the 1960s and early 1970s had
14 Ibid. Note: Unlike other helicopters and aircraft used in search and rescue (SAR) and
relief missions during natural disasters, dedicated air ambulances are specially equipped and
staffed for transporting sick and injured patients. This report only discusses safety data and
issues for dedicated air ambulance aircraft.
15 Barry Meier. “Crashes Start Debate on Safety of Sky Ambulances.” The New York
Times, February 28, 2005.
16 Foundation for Air-Medical Research & Education (FARE), Air Medicine.
17 Ibid.
18 See especially Barry Meier. “Crashes Start Debate on Safety of Sky Ambulances” and
Alan Levin and Robert Davis, “Surge in Crashes Scars Air Ambulance Industry.”
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used helicopters on occasion to transport critical patients, but provided very limited
en route patient care. The air ambulance industry gradually grew during the 1970s
and by 1980 included 32 helicopter emergency services flying 39 helicopters. During
the 1980s, the industry grew fivefold and by 1990 included 174 helicopter emergency
services and 231 helicopters. The industry experienced continued growth in the
1990s expanding to 231 helicopter emergency services flying 400 helicopters by
2000.19
A variety of factors, including increases in Medicare reimbursement rates for air
ambulance services and recent declines in available emergency medical and advanced
patient care services in rural areas, have resulted in a significant growth in the air
ambulance industry over the past five years. In 2005, there were 272 helicopter
emergency services flying 753 helicopters in the United States, roughly an 88%
increase in the number of helicopter air ambulances compared to the size of the
industry in 2000. In 2005, there were also an estimated 150 fixed-wing airplanes
dedicated to air ambulance operations used mostly for inter-hospital transfers.20
Based on industry flight hour estimates, growth in the use of air ambulances has been
increasing at a rate of about 4.5% per year over the past 15 years, and most observers
believe that this steady growth in both the size of the dedicated air ambulance fleet
in the United States and the utilization of air ambulances will continue over the next
several years.
While some states and municipalities and other public agencies operate air
ambulances as public aircraft, most air ambulance services are privately owned and
operated, either directly by a hospital or hospital consortium or by private aviation
medical service providers. The Maryland State Highway Patrol has a comprehensive
helicopter air ambulance capability that covers the entire state, while the California
Highway Patrol and the Virginia and Delaware State Police provide air ambulance
services in portions of those states. Several county police forces and emergency
medical units throughout the United States also perform air ambulance missions.
Also, federally operated aircraft provided by the U.S. Coast Guard in Alaska and the
U.S. Army in Hawaii conduct civilian air ambulance operations. CRS estimates that
federal, state, and local government-operated aircraft currently account for about 10%
of air ambulance operations in the United States. However, private operators make
up the large majority of air ambulance services across the United States.21 Unlike
aircraft that are operated by a state or local agency which are considered public
aircraft and therefore not under direct FAA oversight, air ambulances operated by
private companies are regulated by the FAA, and therefore have been the focus of
safety studies examining safety within the industry and the FAA’s actions to monitor
and regulate safety.22 These private aviation medical providers may operate under
19 Foundation for Air-Medical Research & Education (FARE), Air Medicine.
20 Ibid.
21 See the Association of Air Medical Services (AAMS), Atlas & Database of Air Medical
Services (ADAMS). AAMS National Office, Alexandria, VA for a comprehensive
geographic database of air ambulance service coverage across the United States.
22 CRS is not aware of any study examining the safety of public aircraft used as air
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